Known in the art is a liquid specimen sensor in which a liquid specimen is placed between a pair of IDT (interdigital transducer) electrodes and a property or ingredient of the liquid specimen are measured based on the influence of that liquid specimen exerted upon a signal transmitted and received between the pair of IDT electrodes (for example Patent Literature 1 and 2).
In Patent Literature 1, each of the pair of IDT electrodes is covered by a cover etc. whereby a flow path in which the liquid specimen flows is formed between the pair of IDT electrodes. Due to this, the liquid specimen is guided between the pair of IDT electrodes, and contact of the liquid specimen with the IDT electrodes and connection conductors connecting the IDT electrodes with external terminals is suppressed.
Further, in Patent Literature 2, in a top surface of a space holding the pair of IDT electrodes, a hydrophilic region positioned above the gap between the pair of IDT electrodes and a hydrophobic region positioned just above the pair of IDT electrodes are formed. Due to this, the liquid specimen is guided to the gap between the pair of IDT electrodes, and contact of the liquid specimen with the IDT electrodes and connection conductors connecting the IDT electrodes with external terminals is suppressed. That is, a range forming a flow path is defined not by flow path walls, but by a hydrophilic region.
In the art of Patent Literature 1, covers must be provided, while in the art of Patent Literature 2, a hydrophilic region and hydrophobic region must be formed, so the configuration is complex in both of the cases. As a result, for example, a rise in cost is liable to be invited. On the other hand, unless contact of the liquid specimen with the IDT electrodes and connection conductors is suppressed as in Patent Literature 1 or 2, for example, the permittivity at the periphery of the connection conductors will vary due to fluctuation of the contact length between the liquid specimen and the connection conductors. As a result, the detection accuracy may fall.
Accordingly, provision of a liquid specimen sensor having a simple configuration capable of improving the detection accuracy and a measurement method of a liquid specimen using the liquid specimen sensor is desirable.